1. Technical Field
The invention relates generally to nano-scale filters, and particularly to a nano-scale filter with a filtration membrane having a high specific surface area and high porosity. The invention also relates to a method for making a nano-scale filter.
2. Related Art
A nano-scale filter is widely used for a variety of purposes, such as filtration of nano-particles, absorption of gas, selective passage of fluid, and so on. A conventional nano-scale filter has a ceramic component and a γ-MnO2 filtration membrane sintered on the ceramic component. The ceramic component has a plurality of micro-scale pores defined therein. The filtration membrane has a plurality of nano-scale pores formed by spaces between each two adjacent γ-MnO2 particles. A diameter of each of the nano-scale pores is generally in the range of about 2˜3 nanometers. A diameter of each of the γ-MnO2 particles is generally in the range of about 20˜30 nanometers. A diameter of an aggregation formed by the γ-MnO2 particles is generally in the range of about 100˜500 nanometers. A thickness of the filtration membrane is generally in the range of about 10˜15 microns. With this configuration, a ratio of the number of pores relative to an area of the filtration membrane is relatively small. Thus, this kind of filter has a relatively low filtration efficiency.
What is needed, therefore, is a nano-scale filter with a high specific surface area and high porosity.
What is also needed is a method for making the above-mentioned nano-scale filter.